This application claims the priority of German Patent Application 199 219 66.4, filed May 12, 1999, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an apparatus for condensing a drafted fiber strand in a condensing zone arranged downstream of a front roller pair of a drafting apparatus, comprising a stationary sliding surface, which comprises a suction slit extending essentially in transport direction of the fiber strand, also comprising an air-permeable transport belt located between the fiber strand and the sliding surface, which transport belt transports the fiber strand over the sliding surface.
An apparatus of this type is prior art in, for example, U.S. Pat. No. 5,600,872. During operation, there is a risk that individual fibers of the fiber strand for condensing, in particular the shorter fibers, may reach through the perforations of the transport belt with their front ends to the inside. If the fibers are not suctioned off by means of the suction slit, they are transported further with the transport belt and can, in time, clog the perforations, so that the desired condensing effect no longer occurs.
Condensing of a drafted fiber strand, namely in an area to which the spinning twist is not retroactive, serves to bundle the fiber strand in its cross section and to make it generally less hairy. After the spinning twist has been imparted, a smoother yarn with higher tear-resistance is the result. If, however, due to an impaired condensing effect, the desired condensing does not take place, a so-called Moire effect can occur in the finished fabric, which may render the product a reject. It must therefore be ensured that the condensing effect is not impaired by the clogging of perforations at individual spinning stations.
It is an object of the present invention to ensure that the perforations of the transport belt do not become clogged and that the condensing effect is not impaired.
This object has been achieved in accordance with the present invention in that at a distance from the suction slit, a cleaning element is pressed onto the transport belt using a light pressure.
In the simplest embodiment of the present invention, the cleaning element can, for example, be a stationary scraper-like component, which removes the remaining fibers adhering to the outside of the transport belt. However, an even more suitable cleaning element has proven to be a rotating roller, which can basically be applied anywhere outside of the condensing zone at the periphery of the transport belt. It is hereby important that the speeds of the rotating roller and the transport belt differ from one another, preferably in that the peripheral speeds of the transport belt and of the roller are set in opposite directions. This is the case, for example, when the driven bottom roller of the front roller pair of the drating apparatus is chosen as the cleaning element, as then the directions of motion are automatically set in opposite directions.
The sliding surface advantageously comprises a recess in the area of the cleaning element. This facilitates the cleaning of the transport belt, in particular when a suction device is arranged to the cleaning element and/or the recess.
The cleaning effect can be increased when the rotating roller is provided with a profiling on its peripheral surface.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.